Quote:DEVELOPING: An active shooter was reported Tuesday at the Naval Medical Center San Diego, according to the center’s Facebook page.

The message advises occupants to “run hide or fight.” Non-emergency response personnel were asked to avoid the compound at 34800 Bob Wilson Drive. The center posted that the shooter was believed to be in Building 26.

Fox 5 San Diego reports that three nearby schools are on lockdown.

The U.S. Navy could not immediately confirm the report.

The facility has a staff of more than 6,500 military and civilian personnel, and aims to provide medical care to military service members, their families, and those who served in the past, according to its website.

(CNN)A report of a shooting at Naval Medical Center San Diego appears to be a false alarm, the military indicated Tuesday.

Investigators have found nothing to substantiate one person's report that someone fired gunshots Tuesday morning at the San Diego facility's Building 26, which contains barracks, a gym and administrative offices, Navy Capt. Curt Jones told reporters.

However, authorities at the center's 78-acre campus still were going though the building late Tuesday morning, and it will take a long time to finish their search, he said.

One witness reported hearing three gunshots in the basement of the building -- separate from the main hospital complex on campus -- at about 8 a.m. PT (11 a.m. ET), Navy spokesman Kevin Dixon said.

That prompted a flurry of law enforcement activity, with military and local police searching the building as other officers took up positions nearby, directing pedestrians and cars away from the building in question.